Localization and mapping is a fundamental need for human and mobile agents.
As a motivating example, humans are able to perceive their self-motion and environment via multimodal sensory perception, and rely on this awareness to locate and navigate themselves in a complex three-dimensional space [1]}. This ability is part of human spatial ability.
Furthermore, the ability to perceive self-motion and their surroundings plays a vital role in developing cognition, and motor control [2]}.
In a similar vein, artificial agents or robots should also be able to perceive the environment and estimate their system states using on-board sensors.
These agents could be any form of robot, e.g. self-driving vehicles, delivery drones or home service robots, sensing their surroundings and autonomously making decisions [3]}. Equivalently, as emerging Augmented Reality (AR) and Virtual Reality (VR) technologies interweave cyber space and physical environments, the ability of machines to be perceptually aware underpins seamless human-machine interaction. Further applications also include mobile and wearable devices, such as smartphones, wristbands or Internet-of-Things (IoT) devices, providing users with a wide range of location-based-services, ranging from pedestrian navigation [4]}, to sports/activity monitoring [5]}, to animal tracking [6]}, or emergency response [7]} for first-responders.
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